The blueprint for terror strikes against large, guarded nations such as the United States, Britain, Germany, France, Russia, has changed.

The arrest of Faisal Shahzad reads like something out of novel. From the car left in Times Square on a busy Saturday night loaded with a home made bomb, to witnesses noticing the smoke and flashes of light inside, to the New York mayor being rousted from a black-tie dinner in DC to rush home, to the breathless, last-minute race to the airport to nab the suspect before he went airborne to Pakistan. It makes for great reading when the end comes out right. But it is also a sobering reminder of the fact that sooner or later, the ending will not be what we hope.

And in my experience more security analysts are saying when the next successful attack comes (and given enough time, it will) chances are good it will involve people who are living among us right now.

The blueprint for terror strikes against large, guarded nations such as the United States, Britain, Germany, France, Russia, has changed. Where once the idea was to insert an operative and his team, who would quickly move to launch their assault; now, intelligence agencies talk much more about the danger of legal citizens being radicalized. The equation for recruiters is simple enough: Find a person with religious, political, racial, or ideological ties to your radical cause, no matter how tentative or benign those ties may be. Befriend him. Treat him with respect, and give him opportunities to earn even more of your trust. Find out what is not working for him in the land of opportunity; see what gets under his skin and makes him feel isolated, ignored, put down, disappointed. Then tell him how unfair it is, over and over again. Fuel his fury and his desire for righteous revenge. Then give him a weapon and point him at a target.

We don’t know if that is what happened in this instance, because too many details are still missing. The case of Faisal Shahzad may prove to be an entirely different matter than what I just described. But the cases of so many others are not. We have built up our border security considerably from where it was ten years ago. We have “hardened” some major targets against terror strikes. But we can’t harden them all because there are just too many. And there are too many potential recruits living among us right now; including some of our fellow Americans who, at this moment, are not headed down that path…but who might be in the future.

This is the new front in the effort to stop terrorism, and this is the new question: How do you keep the guy next door from feeling like his best friend is a radical halfway around the world, reaching out through the murky alleys of the Internet, and urging him to kill?